This invention generally relates to an apparatus for detecting a malfunction in the paper feed system of an automatic printer and more particularly relates to such a malfunction detection apparatus which includes means for sensing the presence of a paper jam within the printer and for sensing the depletion of the paper supply therein.
The rapid growth of data communications systems, over the last few years, has greatly increased the demand for high speed alphanumeric printers which type informational data in readable form upon a paper web. Such printers are frequently operated on a continuous basis and require operator attendance only for replacement of an exhausted paper supply or clearance of a paper jam. The paper stationary or forms used in such printers are generally supplied as a continuous sheet with transverse perforations facilitating the removal of selected pages. Additionally, extending longitudinally adjacent the margins of the paper are a series of spaced sprocket holes which are engaged by drive tractors provided on the printer, with the tractors driving the paper across the print mechanism.
A condition, which occasionally occurs during the operation of such printers, is that of a paper jam. On such an occasion, paper movement is inhibited; however, the drive tractors continue to move causing the paper perforations to be torn. Under such circumstances, the print mechanism generally continues to function producing "type-overs" which obliterate the previously typed information with subsequent print being rendered illegible. Occasionally, as a result of operator inattention, the paper supply of one of the printers under the operator's control may become exhausted resulting in a loss of information. Under such circumstances, damage to the ribbon may occur. Thus, it is particularly advantageous for such printers to include means for detecting the presence of a paper drive malfunction and for providing the attendant with a suitable indication as well as means for interrupting operation of the machine when such malfunction occurs.
The illustrated apparatus includes means for detecting the presence of a paper jam in a high speed sprocket printer and for interrupting the apparatus in the presence of such a condition as well as providing a suitable indication of such a paper jam condition. Further, means are included for detecting the condition of the paper supply and for interrupting the printer and providing a suitable indication to the operator when the paper supply is exhausted.